Preheat oven to 300F. In the bowl of a stand mixer, or with a handheld mixer, whisk egg whites and lemon juice on medium speed until frothy and opaque white. Slowly whisk in sugar and continue to whisk on medium-high until stiff peaks form. Fold in lemon zest.
Spoon the meringues onto a parchment or silicone-lined baking sheet in 8 evenly sized circles, keeping them 1 inch apart. Use a spoon to flatten each meringue so that there are no peaks. Bake in the lower half of oven until dried very lightly browned, 40-45 minutes.
Meanwhile, make the lemon curd. In a saucepan, combine lemon juice, zest, sugar and yolks. Cook over medium heat, stirring constantly, until thickened, 5-7 minutes. Note: it won't be as thick as the final product at this point but will coat the back of a spoon.
Strain the curd through a fine mesh sieve and into a clean bowl, to discard any solids (aka scrambled eggs). Whisk in butter until melted. Cover surface of curd with plastic wrap to prevent a skin from forming and place in fridge to cool.
When meringues and curd have cooled completely, break the top of the meringues slightly, fill with lemon curd and top with a dollop of cream and sprinkle of lemon zest. Enjoy!